2281. Ceftolozane–tazobactam (C/T) Treatment Outcomes in Immunocompromised (IC) Patients with Multidrug-Resistant (MDR) Pseudomonas aeruginosa (PA) Infections

BACKGROUND: Evaluations of clinical use and real-world outcomes following C/T treatment exist; however, data assessing outcomes in IC patients are limited. This study evaluated treatment patterns and clinical outcomes of IC patients treated with C/T for MDR PA across 15 US hospitals. METHODS: Adult IC inpatients treated for ≥ 24 hours with C/T admitted between 12/14–5/18 for MDR PA infections were included in this retrospective multicenter cohort study. IC was defined as patients with previous solid-organ transplant (SOT), diseases that suppress resistance to infection (HIV/AIDS, leukemia, lymphoma), or receipt of immunosuppressants, chemotherapy, radiation, long-term low-dose (≥ 1 month) or recent high-dose steroids (> 5 days). Clinical and microbiologic data were extracted from electronic records. The primary outcomes were all-cause 30-day mortality and clinical cure, defined as no escalation/additional therapy and improved signs and symptoms from baseline to end of therapy. PA isolates were characterized as MDR if non-susceptible to ≥ 3 classes of antipseudomonal agents. Classification and regression tree (CART) analysis was used to identify the 30-day mortality split in APACHE II scores. RESULTS: Seventy patients were included; 58 (83%) had received immunosuppressive agents, 47 (67%) had history of SOT, and 19 (27%) had diseases suppressing resistance to infection. Mean patient age was 57 ± 14 years, median (interquartile range) patient APACHE II and Charlson Comorbidity Index scores were 18 (12.5) and 5 (3.75), respectively, with 33 (47%) receiving ICU care at C/T initiation. The most frequent infection sources were respiratory (56%), wound (11%), intraabdominal (10%), and blood and urine (9% each), with 36% having a polymicrobial culture. All-cause 30-day mortality was 19% (n = 13) with clinical cure achieved in 48 (69%) patients. CART analysis identified the 30-day mortality split at APACHE II score > 25 (76% vs. 24%; P = 0.002). CONCLUSION: Of 70 IC patients treated with C/T for MDR PA, clinical cure was achieved in 69% and mortality was 19%, consistent with other evaluations reporting on a cross section of patient populations. C/T represents a promising agent for treatment of PA resistant to many traditional antipseudomonal agents in this high-risk population. DISCLOSURES: Elizabeth B. Hirsch, PharmD, Merck: Grant/Research Support, Research Grant; Nabriva Therapeutics: Advisory Board; Paratek Pharmaceuticals: Advisory Board